Let me clarify a few things here.
This isn't a 'pay2betatest' thing. If it was, we wouldn't be testing it internally right now. We will release a polished demo that will give you access to about 60% of the game.
From another post:
"There are three towns (in total) in the game. That's where all the scheming, plotting, and back-stabbing take place. So, from this point of view, each town is roughly 33% of all that goodness. There are 20+ locations in the game. The + stands for minor stops that we don't count as locations. The first demo had 3: Teron, the raiders' camp, and the mine.
The second demo has 7: Maadoran, the Abyss, the tomb, the mountain pass, the Ordu camp, the tower of Zamedi, and another raiders' camp. So, that's 10, which is 50%. If you like exploring old places that should have stayed buried (similar to the tower and the Abyss), the endgame is where it's at."
We didn't plan to release anything else after the first proper demo (i.e. not the combat one), but it took us longer than we thought and we want to give something to those who have pre-ordered the game, as a way to thank them for their support, since many people have asked for some kind of 'beta participation' or 'early access'."
Those who have pre-ordered do have a right to ask for that and we don't want to tell them no, because some people don't like the practice. That's all there is to it.
So, if you want to wait until the game is out, by all means, do so. I agree that it's better to play a game from start to finish than to play a demo, no matter how extensive and polished. If you don't mind playing demos, if you enjoyed the previous demo and want more, you will be pleasantly surprised. This 'chapter' is bigger and better than the first demo in practically every way.